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  5. The Good, Bad and Bubbly Of Surfactants In Skincare

Do you know what is the most common ingredient in your skincare? Surfactants! From your cleansers to moisturisers and your makeup products, surfactants are present in most of your cosmetics and personal care products.

If you're wondering why and whether you should really buy products with surfactants, stay with us till the end of the article. Let's begin.

What Are Surfactants?

Surfactants are a primary component of cleaning detergents. As the name suggests, surfactants evoke activity on the surface you are cleaning, to help trap dirt and remove it from the surface.

Your soaps, shampoos and hair conditioners contain surfactants, as they help cleanse your scalp, skin, and hair. These compounds create a pleasantly foamy reaction, when mixed with water. They are usually safe for all skin types.

Beyond soaps and detergents, surfactants are also used in lubricants, inks, anti-fogging liquids, herbicides, adhesives, emulsifiers and fabric softeners.

Science Of Surfactants

Let’s dig deeper into how surfactants work chemically. Surfactant is the short form of surface active agents. [1] Surfactants act at the interfaces, such as the oil-water interface or air-water interface. It alters the surface tension (molecular forces) between the two fluids. How do they achieve this?

Surfactants are amphiphilic (amphi: both + philia: love) molecules, that is they have two ends:

  • A hydrophilic head (hydro: water + philia: love) - it is the water loving end that aligns itself towards the water molecules and moves away from oils and fats.
  • A hydrophobic tail (hydro: water + phobia: fear) - this end of the molecule moves away from water and usually aligns with the oils and fats.

When surfactants are added to a solution in sufficient concentrations, they reorganize in such a way that the hydrophilic heads are turned towards the water. The hydrophobic tails capture oil or dirt, forming droplets, also known as micelles [2] (as shown in the image below). With this chemical property, surfactants can be excellent detergents, emulsifiers or foaming agents.

surfactants in equlilibrium

How Are Surfactants Made?

Synthetic surfactants are mostly manufactured using starting materials (reactants used in chemical reactions) such as petrochemicals. These further undergo chemical reactions such as sulfonation (addition of sulphur) or ethoxylation (addition of ethylene oxide). Being synthetic in nature, they can be designed or mixed with other chemicals to serve their desired purposes.

However, there is also a range of biosurfactants that have great advantages as an eco-friendly alternative to synthetic surfactants. These are chemicals produced by microorganisms, but have clearly defined hydrophilic and hydrophobic groups.

Biosurfactants occur in nature. Fungi, bacteria, and yeast are known for producing biosurfactants. They can also be derived from plant-based sources such as coconut and palm oil. [3]

Different Types Of Surfactants

Depending on the charge present on the hydrophilic head of the surfactants, they can be divided into four groups: [4]

Nonionic Surfactants

As the name implies, nonionic surfactants do not yield any net charge in solution. Being mild in nature, these are often the preferred ingredient in cosmetics that do not have foaming or lathering properties.

Nonionic surfactants can be combined effectively with other classes of surfactants. They are commonly used in hand and body moisturisers. Stearyl alcohol, cetearyl alcohol are some of the common nonionic surfactants used in your skincare products.

Anionic Surfactants

These are negatively charged surfactants, good at removing oil and dirt from your skin’s surface. Anionic surfactants are the most commonly used variety as primary detergents in soaps, shampoos and cosmetics having strong cleansing effects. However, they can also be harsh and irritating to your skin.

Such surfactants are often combined with amphoteric or nonionic secondary detergents to cut down on the harshness. Some examples include, SLS (sodium lauryl sulphate), sodium stearate, alpha olefin sulfonate, etc.

Cationic Surfactants

Being positively charged, these surfactants are not effective as detergents and therefore not used in cleansers. The human skin is mostly negatively charged. Thus cationic surfactants tend to attach strongly to it. However, this property makes these surfactants effective carriers of therapeutic products for damaged skin and hair.

Cationic surfactants are also used in fabric conditioners. Quaternary ammonium salts are among the most commonly used cationic surfactants.

Zwitterionic/Amphoteric Surfactants

These surfactants get their name due to the presence of both positive and negative charges in solution. They can adjust the pH of the environment they are added to. Such surfactants can have a calming effect on your skin.

Amphoteric surfactants might be used as secondary surfactants in skincare products to reduce irritation and increase foaming. Betaines, sulfobetaines, certain amino acids and phospholipids are few commonly used amphoteric surfactants.

Common Surfactants Used In Cosmetics

Listed below are some commonly used surfactants in skin and hair care products along with their functions:

Surfactant

Function

SLS (Sodium lauryl sulphate) ALS (Ammonium lauryl sulphate) Olefin sulfonates

Cleansers, foaming agents

Sodium stearate

Soap

Stearic acid

Deodorants, antiperspirants

Cetrimonium chloride Stearalkonium chloride

Hair conditioners

Sodium Lauriminodipropionate Disodium Lauroamphodiacetate

Mild cleansing agents for sensitive skin and hair

Cetyl alcohol Stearyl alcohol

Emulsifiers, thickening agents

Cocamidopropylamine oxide

Foaming agent

Polysorbate ester

Solubilising agent

sodium lauryl sulfate

Role Of Surfactants In Skincare

Surfactants are one of the most extensively used ingredients in the cosmetics industry. The varied chemical properties make them extremely beneficial in personal care products.

Let us see some common applications of surfactants in the cosmetic industry.

1. Detergents or Cleansers

Because of their amphiphilic nature, surfactants can form micelles that trap oil, dirt or sebum. It loosens them from your skin surface, which can then be easily washed away. They are added in products such as soaps, shampoos and face washes.

2. Emulsifiers

Surfactants can be used as emulsifiers, which stabilize the mixture of two immiscible or insoluble liquids such as oil and water, for a prolonged period of time. Emulsifiers are commonly used in creams, lotions, conditioners, etc.

3. Foaming Agents

This group of surfactants reduce the surface tension at the air-water interface. They also enhance lather or bubble formation. A good application of these surfactants is in products like shaving creams, which helps soften the stubble for a smooth shave.

4. Thickeners

Certain surfactants can interact with other ingredients in a formulation, trapping them in a network of the primary surfactant molecules. This results in thickening of the products. These are usually in the manufacture of thick winter body lotions, conditioners for dry hair, mascaras, etc.

5. Wetting Or Dispersing Agents

These surfactants reduce the intramolecular forces at the liquid interface. They also facilitate spread and penetration of the products containing them into the depths of skin and hair. Wetting or dispersion agents are most commonly used surfactants in cosmetic products.

6. Opacifiers

Some surfactants can render a formulation opaque by absorbing light, and making the surface applied on, look brighter. These are commonly used in makeup formulations.

7. Conditioners

Cationic surfactants can form a resilient, protective coating on skin or hair surface.They are commonly incorporated into makeup products, hair conditioners, etc.

8. Preservatives

Due to their bactericidal properties, surfactants can be used as preservatives in cosmetics to prolong their shelf life.

Alternative Surfactants For Your Skin And Hair

Be meticulous while making a choice of surfactants. Not only do they form a large group of ingredients, but are also used in combination with other surfactants and various other ingredients. The interaction between all the ingredients brings out the final effect of the surfactants on your skin.

Avoid using the harsh ones such as SLS or SLES (Sodium laureth ether sulfate). Harsh surfactants can strip your skin of its natural moisture and hasten your skin’s aging process.

Another group of surfactants like PEG (polyethylene glycol), which penetrate deep into the skin, can act as carriers for potential carcinogens (cancer-causing).

Natural surfactants, which are derived from plant sources, are relatively safer to use. They undergo a certain degree of chemical processing in order for them to be suitable for use in cosmetics. Some natural surfactants are potassium cocoate (derived from coconut oil), decyl glucoside (from corn and coconuts), sucrose cocoate (from sugar beets), etc.

Most of SkinKraft’s customized skin and hair care products are formulated with natural surfactants derived from coconut or palm oil and corn glucose. They clean your skin and hair gently without stripping off its essential oils.

Interactions Between Surfactants And The Skin

Surfactants present in a product may interact with the skin primarily in two ways:

1. Interaction with SC

Surfactants can interact with the stratum corneum (SC), the outermost layer of your skin. The surfactants form monomers or polymers, which can penetrate the skin barrier and moisturize deeply.

However, prolonged usage of strong or harsh surfactants can permanently alter the cell structure of your skin surface. This can damage your skin’s barrier function and cause inflamed skin.

2. Altering the pH

Depending on the net charge upon dissolution, surfactants can affect the pH at your skin surface. [5] Products with high pH levels can make your skin dry and itchy, and cause acne breakouts.

Use formulations with an optimally balanced pH. Temporary usage of mildly acidic cleansers can help you reduce acne breakouts. If you have eczema or dermatitis, slightly alkaline cleansers can help.

skin cleaning steps

Wrapping Up

There is no way we can do without surfactants in our daily lives. Whether washing dishes, cleansing your face or doing a load of laundry, surfactants make cleaners work better. Thus, the safest option is to be aware of the surfactants present in the products you use regularly. Try and use the milder versions whenever possible. Also, try buying products from manufacturers, who consciously declare their products to be free of harsh chemicals like SLS and parabens.

Begin By Knowing Your Skin

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